const gulp = require('gulp'),
      htmlmin = require('gulp-htmlmin'),
      connect = require('gulp-connect'),
      uglify = require('gulp-uglify'),
      babel = require('gulp-babel'),
      sass = require('gulp-sass'),
      cleancss = require('gulp-clean-css')




//制定一个压缩html的任务
gulp.task('html', () => {
    gulp.src('src/**/*.html')
    .pipe(htmlmin({
        removeComments: true,//清除HTML注释
        collapseWhitespace: true,//压缩HTML
        collapseBooleanAttributes: true,//省略布尔属性的值 <input checked="true"/> ==> <input />
        removeEmptyAttributes: true,//删除所有空格作属性值 <input id="" /> ==> <input />
        removeScriptTypeAttributes: false,//删除<script>的type="text/javascript"
        removeStyleLinkTypeAttributes: true,//删除<style>和<link>的type="text/css"
        minifyJS: true,//压缩页面JS
        minifyCSS: true//压缩页面CSS 
      }))
      .pipe(gulp.dest('dist'))
      .pipe(connect.reload())
})

//指定CSS任务
gulp.task('css', () => {
  gulp.src('src/css/**/*.scss')
    .pipe(sass())
    .pipe(cleancss())
    .pipe(gulp.dest('dist/css'))
    .pipe(connect.reload())
})

//指定js任务
gulp.task('js', () => {
    gulp.src('src/js/**/*.js')
      .pipe(babel({
        presets: ['@babel/env']
      }))
      .pipe(uglify())
      .pipe(gulp.dest('dist/js'))
      .pipe(connect.reload())
})

//制定一个开启服务器任务
gulp.task('server', () => {
    connect.server({
        root: 'dist',
        port: 1908,
        livereload: true
    })
})

//制定一个img任务
gulp.task('img', () => {
    gulp.src('src/images/**/*')
      .pipe(gulp.dest('dist/images'))
})

// 制定libs任务
gulp.task('libs', () => {
    gulp.src('src/libs/**/*')
      .pipe(gulp.dest('dist/libs'))
})

//指定一个watch任务
gulp.task('watch', () => {
    gulp.watch('src/**/*.html', ['html'])
    gulp.watch('src/js/**/*.js', ['js'])
    gulp.watch('src/css/**/*.scss', ['css'])
})

gulp.task('default', ['html', 'js', 'css', 'server', 'img', 'libs', 'watch'])